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Message-ID: <4F2C5429.3080406@candelatech.com>
Date: Fri, 03 Feb 2012 13:39:53 -0800
From: Ben Greear <greearb@...delatech.com>
To: Eric Dumazet <eric.dumazet@...il.com>
CC: Shawn Lu <shawn.lu@...csson.com>, davem@...emloft.net,
netdev@...r.kernel.org, xiaoclu@...il.com
Subject: Re: [PATCH] tcp: RST: binding oif to iif for tcp v4
On 02/03/2012 01:31 PM, Eric Dumazet wrote:
> Le vendredi 03 février 2012 à 12:16 -0800, Shawn Lu a écrit :
>> Binding RST packet outgoing interface to incomming interface
>> for tcp v4. This has few benefits:
>> 1. tcp_v6_send_reset already did that.
>
> I dont think so. ipv6 makes no special provision for RST.
>
>> 2. This helps tcp connect with SO_BINDTODEVICE set. When connection
>> is lost, we still able to sending out RST using same interface.
>
> I dont understand this.
I have been using a similar patch for years now. When using routing
rules that depend on binding to an interface, the RST isn't always bound
properly without this fix.
My code looks like this:
@@ -650,6 +650,7 @@ static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
arg.iov[0].iov_len, IPPROTO_TCP, 0);
arg.csumoffset = offsetof(struct tcphdr, check) / 2;
arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;
+ arg.bound_dev_if = skb_rtable(skb)->rt_iif;
net = dev_net(skb_dst(skb)->dev);
ip_send_reply(net->ipv4.tcp_sock, skb, ip_hdr(skb)->saddr,
It was originally written by Patrick McHardy, but I've hacked it
a bit over the years to keep it compiling. It seems to work fine.
Thanks,
Ben
--
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc http://www.candelatech.com
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